Physics Nobel 2019 Is About Understanding the Universe

The Physics Nobel prize this year has been shared by an astrophysicist for his theoretical predictions about how matters from the Big Bang eventually swirled into galaxies along with two astronomers who showed that other stars like the sun also have planets revolving around it—the exoplanets.

Princeton University Professor Emeritus James Peebles is the astrophysicist who won the Nobel for his seminal theoretical predictions about the early universe and formation of galaxies. The prize is shared by Michael Mayor, an astrophysicist and an emeritus Professor at University of Geneva, and Didier Queloz, a physics Professor at the Cavendish laboratory at Cambridge University. They were the first to discover a planet that circles around a distant sun like star.

It seems that the two research fields are vastly different in scope and topic, but they share one thing, their research is about how to acquire a better understanding of the universe and also about where we are in the universe. Ulf Danielsson, a member of the Nobel selection committee said—“Really, sort of tell us something very essential—existential—about our place in the universe”.

Peebles’s Life Long Research

James Peebles has been devoted to understanding the mysteries of the universe for at least 5 decades now. In his early part of research, back in 1960s, many aspects about the universe were some rough guesses, whether it is the cosmological distances or the age of the universe. There were very few observations to have a general idea about what the universe is. Peebles has since been able to contribute to the field of cosmology a solid mathematical foundation to understand the evolution of the universe.

In 1964, Arno Penzias and Robert Wilson, the two radio astronomers discovered that microwaves pervade all of the universe. They were conferred with the Physics Nobel for it in 1978. This discovery perplexed them until they encountered what theoreticians calculated, including Peebles. James Peebles and his colleagues predicted that microwaves should be all pervading as a background radiation of the Big Bang. His calculations tell that after almost 4,00,000 years of the Big Bang, the universe started cooling so that hydrogen and helium atoms were formed. The microwaves that were detected were the residue of this cooling of the universe 4,00,000 years back. This was an incredible theoretical prediction.

The background microwave was uniform in all directions, with a temperature just a few degrees above the absolute zero. Peebles calculated that, in whatever way the microwaves look uniform, there should be faint fluctuations and it is these fluctuations that reflects the regions where matters have clumped together that eventually formed the stars in the galaxies, and the clusters of galaxies. 

During early 1980s, Peebles came up with the idea that the universe is filled with “cold dark matters”. These mysterious particles don’t interact with ordinary matter but their enormous gravitational pull formed the galaxies and the clusters of galaxies.

Around 1990s, Peebles’s theoretical predictions started having solid observations. Scientists measured some fluctuations in the microwave background and also a NASA mission named as the cosmic background explorer acquired a considerable amount of data that proved Peebles was right.

The Physics Nobel in 2011 was actually for discovering that the universe is not only expanding, but accelerating—an idea that Peebles calculation also predicted. 

Discovery of Exoplanets

Astronomers have long believed that there are other sun-like stars that possess their planets circling around. This idea formed a quarter century back could not have direct observation of such an object till 1995. In October 1995, Michael Mayor and Didier Queloz announced to have detected a Jupiter sized gaseous one, orbiting a sun like star in our own galaxy, the Milky way. Using custom made instruments at the haute Provence observatory in France they could see the exoplanet, named as 51 Pegasi b. The star that this planet revolves around is 51 Pegasi, which is similar to our sun and is 51 light years away.

Their discovery revolutionised the field of astronomy and since then over 4,000 exoplanets have been detected. Detecting the exoplanet for the first time was an extremely difficult task. Planet 51 pegasi b is as large as the Jupiter of the solar system and they expected it to have a longer revolving period around its star. But to their utter surprise, 51 pegasi b was found to revolve around its star in just four days. Later, they concluded that this could happen only because 51 pegasi b was incredibly near to its star. This was the starting point that provided a new understanding about planetary systems outside the solar system.

Taken together, these two streams of researches have transformed our ideas about the cosmos. While Peebles’s works have established a framework to understand how the universe has evolved since the Big Bang, Mayor and Queloz’s works have expanded the horizon of our knowledge about the planetary systems by their hunt for unknown planets.